Effect of fenpiclonil on phosphorylation of glucose in Fusarium sulphureum

The phenylpyrrole fungicide fenpiclonil inhibited the metabolism of glucose in mycelium of Fusarium sulphureum Schlecht at a concentration which only slightly inhibited mycelial growth (EC15). At the same concentration, fenpiclonil also inhibited accumulation and, to a greater extent, phosphorylation of 2‐deoxy[U‐14C]glucose in starved mycelium loaded with unlabelled 2‐deoxyglucose. Fenpiclonil did not affect cell‐free phosphorylation of 2‐deoxyglucose or the ATP content of mycelium. Therefore, the primary mode of action of the fungicide may be based on inhibition of transport‐associated phosphorylation of glucose. This may cause a cascade of metabolic events which eventually lead to fungal growth inhibition and death. One major event affected by inhibition of transport‐associated phosphorylation is the accumulation of polyols, such as glycerol and mannitol, in mycelium. This was not observed in an osmotically sensitive, fenpiclonil‐resistant laboratory isolate of the fungus.